Brakes: 6cyl GT Hawk using V8 wheel cylinders or the smaller 6cyl car slave cylinders

[go-studebaker]

Hi blokes,
I have a very low milage Belgian assembled GT 6cyl stick shift (no OD) from Belgium in the garage at the moment. Since it hasn't been run for 10 years, I am doing the usual checks one does before starting and getting it ready for UK registration.

Anyway, 3 of the slave cylinders are toast. They are the standard ones used on 6cyl cars 1" die on the front and 13/16" on the rear.

On the shelf here I have new V8 ones which are 1 1/16" front and 7/8" rear.

Not having any familiarity with 6 cylinder later cars am I heading for trouble if I use a set of V8 ones in the car ??? My gut feel is that with the extra weight it may make it a bit easier to stop.

I presume the same problem may be encountered on the 6cyl earlier Hawks that were available state side. Master cyl is off and looks fine so far and I have a kit for it. I have new rubber flex hoses to go back on as well, so all bases will be covered.

I would appreciate your comments.



Thanks
Greg

[63 R2 Hawk]

Larger wheel cylinders would increase the distance the master cyl needs to travel to apply the brakes since they would displace more fluid, so you could end up with a pedal that goes too close to the floor when brakes are applied or possibly run out of travel. What size are the drums? I'm pretty sure those original wheel cylinder sizes are readily available from Stude parts dealers, so it's probably not worth experimenting with wheel cylinders.

[bensherb]

What size is your master cylinder bore? If its the same 1" one the V8 Gt has you should be fine.

[t walgamuth]

I'd just try them. I imagine with the better grip of modern tires they'll be perfect.

[christophe]

Hi Greg,
Looks like you're very busy these days!
When I overhauled the brakes on my 63, I found all the hydraulic parts at Rockauto's. I don't recall what it cost, but they were not expensive. I advise you against doing this. I discovered many years ago with my SIMCA 9 that even a slight size variation made the difference between a safe car and a car with a spinning rear end on wet pavement! In case your brake linings are bonded, you should check that their adhesion to the shoe is still strong. I had the surprise to see mine separate when putting them (gently!) on the ground.
Best of luck with your two nice cars.

[go-studebaker]

Hi guys and Christophe.
I have morphed into a European with 6 cyl cars for change......

Yesterday I reassembled the brakes using the V8 slave cylinders and took the car out for a spin around the property. The V8 slaves are only 1/16th larger than the 6cyl ones.
The car stopped surprisingly well with V8 slaves in it. Hawk master cylinders are the same for V8's and 6cyl cars so the fluid problem and brake pedal travel are no real issue.

Before I went out for the drive, I decided to clean out the car of all the junk and vacuum it out. A long dead mouse was found in the back seat.
However, inside a box on the passenger side rear floor area was a new set of 6cyl slave cylinders........

Driving a stick shift GT with an OHV 6 was interesting. The car is definitely not as fast as a V8 by a long shot, but motors along quite fine.

Once it is registered I will be able to test it out properly.

If I get a set of larger V8 Hawk brakes, I will change the car over at a later date.

Anyway, I am more than happy with the 'brake feel' and stopping power the car has to be more than comfortable the way it is. But I will review it on wet pavement when I have the car registered.

Regards and thanks for your input,
Greg

[christophe]

Hi guys and Christophe.
Driving a stick shift GT with an OHV 6 was interesting. The car is definitely not as fast as a V8 by a long shot, but motors along quite fine.

Sans OD, its soft spot is around 55 mph. One nice thing is that, except on mountaineous roads, you keep the 3rd gear all the time. As for the stopping power, I find it adequate with the small drums so far but never tried it in the Alps!
Sorry if I'm curious but what is the purpose of the triangular support located by the battery tray?

[go-studebaker]

Hi Christophe,
the triangular support is the top battery hold down falling off and is really rectangular.

Regards
Greg

[christophe]

Hi again Greg,
OK, I got it now.
Nice day to you and all the others.

[Steve Winzar]

Hi Greg- If you have used slightly larger bores all around I assume you are feeling less pedal pressure- is that the case? And I don't see a Power brake Booster anywhere, so I'm just wondering how the brakes 'feel' under foot now. No need of PB assistance?
BTW, nice presentation on "Classic Connection'- well done, cobber
Regards, Steve W in Melbourne.

[stude dude]

Hi Greg, that is an interesting Hawk! I have never seen a 6 cylinder GT Hawk so am curious about a couple of things -

Having a single exhaust system, does the rear lower panel have just the one cutout?
Does it have a tacho?
Is the boot lid emblem R/W/B or solid white?

Thanks, Chris.

[christophe]

My 63 model has:
- one cutout
- no tach
- transparent emblem
There are other pecularities due to the fact that car is an export model assembled in Belgium.
I suspect Greg's one is just the same.
Nice day to all.

[t walgamuth]

using one size larger wheel cylinders keeping with the original size master will make the brakes require less pedal pressure to work. Its not a huge difference but definitely noticeable.